President Moon Jae-in’s special adviser said Friday that South Korea should not be pushed around by the US as the allies seek to build a united front against North Korea, in a veiled criticism of President Donald Trump’s blunt remarks that South Korea can do nothing without his approval.

During a security seminar with a renowned US security expert in Seoul, Moon Chung-in said Trump should have been more careful with his choice of words instead of making “impromptu, instantaneous” remarks that have been widely criticized in Seoul as a diplomatic insult.

Trump said Wednesday that without his approval of sanctions relief against North Korea, South Korea would not be able to do anything about the matter, including the lifting of its own sanctions on North Korea imposed in 2010 after Pyongyang’s suspected torpedo attack on a South Korean Navy corvette.

“(Trump) knows that the US cannot force us” to accept his opposition to the lifting of South Korea’s own sanctions, Moon Chung-in said at a security seminar hosted by the Yonsei Institute for North Korea Studies and East Asia Foundation, during which 38 North Director Joel Wit delivered the main speech.

“He might have been confused between consultation and approval,” Moon added.

Presidential special adviser Moon Chung-in. Yonhap

Wit, who was involved in previous nuclear talks with Pyongyang before running the North Korea-focused website 38 North, agreed that Trump made “insulting and inappropriate” remarks and should have chosen his words more carefully.

“What he should have said was, well, we are allies in this together, we have to consult, work together and talk to each other about how to deal with sanction issues,” Wit said. “That’s the right thing to say and behind closed doors we could fight it out. I have seen this over and over again.”

The bilateral scuffle began Wednesday when Foreign Minister Kang Kyung-wha told lawmakers that consultation was underway with relevant ministries about lifting South Korea’s own sanctions on North Korea.

While Kang and Unification Minister Cho Myoung-gyon walked back the comments, conservative lawmakers expressed concern over whether there is a rift between Seoul and Washington in their stances on sanctions relief for North Korea.

Washington insists that sanctions remain in place until significant progress is made on denuclearization, but speculation has been rampant that Seoul might eventually seek to lift its unilateral sanctions to foster inter-Korean projects.